Search PubMed⌕ Search

Biomedical subjects

Z Chen

Publications and source records attributed to Z Chen.

At least 307 records · Page 17Linked to original sources

The role of the dentist in detection of carotid atherosclerosis.

Cerebrovascular accidents (CVA), or stroke, afflict 731,000 Americans each year, with 165,000 of these individuals dying. Stroke is a major cause of death and disability throughout the world, including southern Africa. Atherosclerosis-related formation of thrombi and emboli at the bifurcation of the common carotid artery and proximal internal carotid artery represents a common cause of stroke. The detection of carotid atherosclerosis by dentists using panoramic radiographs recently has been presented to the public through television news stories and the press, but many dentists still do not know how to interpret panoramic radiographs for detection of this condition. This communication illustrates examples in which carotid atherosclerosis was detected using panoramic radiography. Differential diagnoses are presented. Since not every carotid plaque calcifies, panoramic radiography should never be used alone to exclude the possibility of carotid atherosclerosis. It should also be remembered that the mere presence of calcified carotid plaque is not necessarily a reflection on the degree of carotid stenosis. Definitive diagnosis and treatment requires referral of patients deemed to be at risk to an appropriate physician. A variety of advanced diagnostic methods, including gadolinium-enhanced MRI, Duplex Doppler sonography and angiography are used to confirm carotid stenosis.

Angiography↗

[Management of arterial occlusive diseases of abdominal aorta and iliac artery: experience with 267 cases].

OBJECTIVE: To study the surgical treatment of infrarenal aortic and iliac arterial occlusive disease. METHOD: We analyzed 267 patients with arterial occlusive diseases of the abdominal aorta and iliac artery retrospectively. RESULTS: All the patients were treated by surgery including aortic-iliac bypass in 145 patients, iliac-femoral bypass in 40, femoro-femoral bypass in 45, and axillo-femoral bypass in 37. Their total effective rate and perioperative mortality were 96.5% and 3.5%, respectively. Of the 267 patients, 178 were followed up. The patency rate of prosthesis was 82.0%. CONCLUSIONS: Extra-anatomical bypass is a procedure of choice for high-risk patients, especially for those chronic patients with coronary heart disease, hypertension, cerebral arterial atherosclerosis, and brain infarction.

Adult↗

[Expression and drug resistance of human MGMT gene in hemopoietic cells mediated by bicistronic retroviral vector].

OBJECTIVE: To increase myeloid progenitors resistance to chemotherapy and prevent myelosuppression caused by alkylating agents. METHODS: Total cellular RNA was extracted from human liver and cDNA was synthesized by superscript reverse transcriptase, a polymerase chain reaction(PCR) was conducted. We obtained a full length cDNA fragment encoding human alkyguarine-DNA-alhyltransferase(MGMT). The PCR product was cloned into pGEMT-T vector and further subcloned into G1Na retrovirus expression vector. Then the recombinant plasmid was transduced into the packaging cell lines GP+E86 and PA317 by lipofect AMINE. RESULTS: By using the medium containing BCNU for cloning selection and ping-ponging supernatant infection between ecotropic produced clone and amphotropic producer clone, we obtained high titer amphotropic PA317 producer clone with the highest titer up to 8.6-10 CFU/ml. Human hematopoietic cells were infected repeatedly with this high titer virus under stimulation of hemopoietic growth factors IL-3, IL-6 and SCF. PCR, RT-PCR, Southern blot, Western blot and MTT analyses showed that MGMT gene has integrated into the genomic DNA of human hemopoietic cells and expressed efficiently. CONCLUSIONS: This study provides a foundation for application of gene therapy to tumor clinical trial.

Alkyl and Aryl Transferases↗

[Establishment and characterization of three transplantable tumors of nasopharyngeal carcinoma in Scid mice].

BACKGROUND: To establish several transplantable tumors of nasopharyngeal carcinoma (NPC) in order to provide suitable models for study of EBV specific immunity and its application in treatment of NPC. METHODS: Balb/C nude mice and scid mice were used as transplantation host. Tumor tissues were obtained with forceps from nasopharyngeal tumors of twenty six untreated NPC patients and transplanted subcutaneously in axilla or back of mice with puncture trocar. Characteristics of the established transplantable tumors including the transplanting efficiency, growth rate, gross appearance morphology under optic microscope and electron microscope and karyotypes chromosome were investigated. Detection of LMP-1 as well as LMP-2 were performed for the transplantable tumors and cell lines with immunohistochemical methods. RESULTS: Three transplantable tumors were successfully established from 26 specimens of human nasopharyngeal carcinoma and mamed as CSNET-1, CSNET-2 and CSNET-3. The CSNET-1 was primarily generated in nude mice and then transplanted to scid mice after 3 passages. To date the CSNET-1, CSNET-2, CSNET-3 have been passed to 11th generation (23 months), 14th generation (17 months) and 9th generation (16 months), respectively. The overall success rates of transplantation were 91% (39/43), 97% (29/30) and 94% (34/36); The median time of latent growth were 23, 38 and 20 days;and longest persistence of tumor in vivo were 93, 38 and 44 days, respectively, for the above tumors. The karyotypes of all transplantable tumors displayed as typical human origin with hyperdiploid chromosomal and multiple structure aberration. Histologically, the tumors possess the characteristics of poor differentiated squamous carcinoma under either microscope or electron microscope. Some particles minimizing mature EBV were found in CSNET-1 under electron microscope. Either LMP-1 or LMP-2 were detectable in CSNET-1, CSNET-2, and CSNET-3 by immunohistochemical test. CONCLUSIONS: The transplantable tumors CSNET-1, CSNET-2 and CSNET-3 are of human origin and able to pass steadily in scid mice. They possess the characteristics of poorly differentiated squamous carcinoma similar to their prime tumors in human and express EBV LMP-1 and LMP-2. These tumors seemed to be suitable models in the study of immunotherapy for NPC.

Animals↗

[Detection of enterovirus RNA in cerebrospinal fluid from patients with aseptic meningitis and encephalitis and its clinical significance].

BACKGROUND: To study the pathogenicity of enterovirus (EV) infection in central nervous system and the method for its detection. METHODS: Using reverse transcription polymerase chain reaction (RT-PCR) and viral culture techniques to detect EV from 46 cerebrospinal fluid (CSF) samples of aseptic meningitis and encephalitis patients. The sensitivity and specificity of RT-PCR for EV RNA detection was affirmed by specific RNA identification of 40 strains of prototype enterovirus. RESULTS: By the virus culture method, 14 out of the 46 CSF sample were tested to beEV positive (26.1%) including 6 Echovirus type 2 (ECV2), 2 Coxackie virus type B2 (CVB2), 2CVB6, 1 ECV3 and 1 ECV11. By RT-PCR method, 31 of 46 CSF sample were tested EV RNA positive (67.4%) through amplified product agarose electrophoresis and northern blot hybridizition. The positive CSF included 14 samples that had been tested positive by virus culture and 17 samples that accounted for 53.9% of the 32 CSF samples which were negetive by virus culture. The sensitivity of RT-PCR was statistically higher than that of the virus culture method, Chi(2) =12.57, P <0.01. CONCLUSIONS: EV is known as important etiological agents of aseptic meningitis and encephalitis. RT-PCR is sensitivity, specificity and rapidity, it may be popularized as an effective method to the detection of enterovirus.

Adolescent↗

[An experimental study on the implantation of a biomaterial with electro-activity for replacement of hard tissue in bone].

OBJECTIVE: To assess the effects of a piezoelectric biological ceramic on osteogenesis. METHODS: Hydroxyapatite (HA) and piezoelectric biological ceramics (hydroxyapatite and barium titanate, HABT) were implanted in the jawbones of 5 dogs, and for sample collection, the dogs were killed separately at 1 week, 2 weeks, 1 month, 2 months and 3 months after implantation. The samples from a rhesus monkey and a blank control were collected 34 months after implantation. The implanted samples and surrounding tissues were subjected to histological observations using light microscopy (LM) and scanning electronmicroscopy (SEM) were made. RESULTS: Compared with the control groups, the HABTs promoted osteogenesis significantly. One week after implantation, new bone tissues were found on the surface vertical to the longitudinal direction of HABT; more bone tissues were found after 2 weeks. HABTs induced the bone tissues to arrange orderly. After two years and ten months of implantation, the piezoelectric bioceramic and bone became monolithic, and the structure of bone was normal. CONCLUSION: HABTs could promote osteogenesis.

Animals↗

[A comparison of the kinetic characters of NT-3, NT-4 and BDNF retrogradely transported in facial nerve].

OBJECTIVE: To compare the kinetic characters of retrograde transport of neurotrophin-3 (NT-3), neurotrophin-4 (NT-4) and brain-derived neurotrophin factor (BDNF) in facial nerve. METHODS: Radioactive tracer technique was used. After one lateral facial nerve trunk of adult rabbit was transected, a silicone chamber was inserted between the stumps, and 3.7 MBq of 125I-NT-3 or 125I-NT-4 or 125I-BDNF or 125I-HSA was administered into the chamber. At different time-points after injection, the facial nerve trunk and facial nerve motor neurone of brain-stem were collected and the uptake rates were measured. The kinetic parameters of each labeled compound were calculated using 3P87 program of kinetics. RESULTS: The transport amount of neurotrophin retrogradely transported by facial nerve is NT-3 > BDNF > NT-4 (P < 0.05), the transport rate is NT-4 > NT-3 > BDNF (P < 0.05). CONCLUSION: The findings could serve as the kinetic characters of retrograde transport of neurotrophins.

Animals↗

[The blood drainage of Langerhans islets with special reference to the functional and clinical significance of pancreatic exocrine part].

OBJECTIVE: This study sought to gain an insight into the blood drainage of Langerhans islets with special reference to the functional and clinical significance of pancreatic exocrine part. METHODS: Observations were carried out in 11 human dead bodies, 40 monkeys, 24 dogs, 62 rats and 24 rabbits by scanning electron microscopy and light microscopy with the technique of retaining microcirculatory dynamic and tissular information in the static specimens, microvascular serial reconstruction, and/or by intravital fluorecence microscopy with FITC-labeled erythrocytes. RESULTS: Three patterns of islet drainage channels drained into different acinar regions with different features and insulo-insular drainage channels observed in the primates were found in this study. The authors suggest that these patterns might be termed as follows: 1. Continuous drainage vessels. All islets possessed these capillary-sized portal vessels which ran a short distance, and then drained into the peri-islet acinar region. 2. Convergent drainage vessels. Some islets possessed one or two, occasionally more, of these portal vessels, which were relatively long and/or thick and drained into the acinar region far away from the islet in the lobule. 3. Translobular drainage vessels. These portal vessels crossed the interlobular septum into an adjacent lobule where sometimes no islet existed, and then drained into the exocrine acinar region 4. Insulo-insular drainage vessels. Some islets in the monkey and human, possessed these vessels which drained into an adjacent small islet through the insulo-insular drainage vessels. CONCLUSION: Langerhans islets possessed the consummate drainage system which drained into different exocrine acinar regions, suggesting that the release of islet hormones is in some way necessary for the exocrine secreting function, and that the reduction of local insular hormone levels in insuloacinar portal circulation and the impairment of insular drainage vessels would be the morphological basis of the pancreatic exocrine pathologic lesion in human diabetes.

Adult↗

[Factors involved in intelligent development of children with cleft lip and palate].

OBJECTIVE: The objective of this study was to investigate the possible factors involved in intelligent development of children with cleft Lip and palate. METHODS: The intelligence quotient (IQ) and developmental quotient (DQ) of 152 children with cleft lip and palate under 14 years old were conducted, and the control group was made up of 80 healthy children. The considered factors included degrees of deformation, situation of perinatal period, way of feeding, psychological conditions of the children, general situation of their parents and education of these children. The data were statistically analyzed and compared. RESULTS: The IQ value of these children generally was normal, but the mean value was still lower than that of the control group (P < 0.01). The mean IQ value of the group of children with only cleft lip or cleft palate was higher than that of the group with both cleft lip and cleft palate, and the mean IQ value of these children with II degree deformity was higher than that of children with III degree deformity. The mean IQ value of these children feed with mother's milk was higher than that of those feed with artificial milk. These children more than 5 years old were disturbed psychologically, and their parents were also with pressure. CONCLUSION: The intelligent development of children with cleft lip and palate is affected by many factors, including types and degrees of deformity, feeding ways, illnesses and social psychological factors in different periods of development. Therefore, it is very important to take steps before 5 years old, including correctly feeding, repairing the deformity as early as possible, preventing the illnesses, necessary psychological treatment, improving social environment.

Adolescent↗

[Comparison of the effect of fluoride and non-fluoride dentifrices on enamel demineralization and remineralization in vitro].

OBJECTIVE: The purpose of the experiment is to investigate the effect of fluoride dentifrices in China on the intact and artificial caries-like bovine enamels. METHODS: The artificial caries-like lesions were created by dipping the teeth into an acid buffered solution. Both the bovine intact enamels and the artificial caries-like enamels were assigned tooth brushing 20 times every half an hour with 3 kinds of fluoride dentifrices and one kind of non-fluoride dentifrices respectively. The amount of calcium dissolved by lactic acid was determined as the susceptibility of demineralization by atomic adsorption spectrometry (AAS). RESULTS: The group treated with fluoride dentifrice showed significantly less demineralization than the non-fluoride group (P < 0.02). The effect of inhibition of acid solubility in artificial caries-like enamel after tooth brushing is significantly greater than that in intact enamel. CONCLUSION: Fluoride dentifrices in this experiment can prevent both intact enamel and artificial caries-like enamel from acid solubility after tooth brushing, and it seems that the effect of the fluoride dentifrices on the redemineralization is greater than the reduction of enamel solubility.

Animals↗

[Clinical significance of trigeminal neuralgia treated using radiofrequency thermocoagulation (RFT) with different approaches].

OBJECTIVE: The authors presented the short term and long term effects of the trigeminal neuralgia treated by RFT with anterior-lateral facial, lateral facial and trans-subzygomatic approaches. METHODS: 320 primary patients with trigeminal neuralgia were selected for this study. All these patients were followed up with the period of 1 to 6 years. RESULTS: The first-time effective ratios of pain-relieve treated by using the anterior-lateral facial approach, and the lateral facial and the trans-subzygomatic, were 93.3% and 73.3% respectively. Most of the patients (92.5%) achieved excellent or good pain-relieve after treated by one of these three approaches. Compared with the lateral facial and trans-subzygomatic procedures, the anterior-lateral facial approach caused less recurrent rate in long term effects (P < 0.01). The late recurrence was found in 93 patients, but pain-relieve effect still could be obtained by retreating with the former method and without difficulty or hazard. One patient had serious Rollets syndrome. CONCLUSION: It is concluded that the anterior-lateral approach is a method with more effective pain-relieve and less pain recurrence rate, and the trans-subzygomatic method can be used as a substitutive approach in the treatment of the second branch of trigeminal neuralgia.

Adult↗

[One stage otoplasty treatment for congenital malformations of the auricle and middle ear].

OBJECTIVE: To investigate the application of one stage otoplasty for congenital atresia of the external acoustic canal and malformations of the middle ear and the auricle. METHOD: Patients with the ear malformations were given surgical reconstruction of one stage otoplasty. The auricle was reconstructed with the rib which was encapsulated with the superthin temporal flap. According to the malformations of the middle ear in patients, I style tympanoplasty and III style tympanoplasty were carried out respectively. All patients were performed myringoplasty with temporal fascia and reconstructed the external acoustic canal with full thickness skin-grafting. RESULT: A long term follow-up (4-6 years) demonstrated that 11 ears were survival of which 8 ears figuration were ideal. The hearing improvement was observed in all patients. CONCLUSION: One stage otoplasty is effective for treatment of the congenital malformations of the external and middle ear.

Adult↗

[The influence of IL-2 on the immunologic function of the NPC patients treated with radiotherapy and chemotherapy].

OBJECTIVE: To investigate the combining therapy which not only have cured effect but also can uphold and improve the NPC patient's immunity function after radiotherapy and chemotherapy. METHOD: 90 cases randomly divided into 3 groups 1. Local group (local injected with IL-2 + radiotherapy + chemotherapy); 2. General group (ivdrip with IL-2 + radiotherapy + chemotherapy); 3. Convention group (radiotherapy + chemotherapy). Checked and observed the immunity function around the immunotherapy and after the radiotherapy and chemotherapy. RESULT: Cellular immunity of 3 groups are lower and humoral immunity are hypetuntion than normal person. After treated with IL-2 the cellular immunity improves but there's no great change of the humoral immunity. The immune status of the immune groups have not obvious change than before radiotherapy, at the same time, the cellular immunity of the convention group cut down and the humoral immunity doesn't change obviously. CONCLUSION: 1. It has some effect to uphold and improve the NPC patient's immunity function to treat with small dosage of IL-2 before radiotherapy and chemotherapy, general treatment is better than local injection; 2. The three therapies have not great influence on the patient's humoral immunity.

Adult↗

[Expression of rice dwarf virus outer coat protein gene(S8) in insect cells].

Outer coat protein gene(S8) of RDV was cloned into the transfer vector pVL 1393 to construct a recombinant vector pVL1393-S8. The recombinant vector pVL1393-S8 and the linear baculovirus RP23. LacZ were cotransfected into sf9 cells to produce the recombinant virus RP23-S8. RP23-S8 infected sf9 cells were collected and analysed by SDS-PAGE and Western-blot. The results showed that the S8 gene of RDV was expressed in sf9 cells and the expression level of sf9 cells was higher between 72-96 h after infected.

Animals↗

[Some biological characteristics of genetically engineered insecticidal Pseudomonas fluorescens].

Plasmid stability, Antifungal activity, plant-colonizing ability, UV resistance and inseticidal activity in field were analysed for the engineered Pseudomonas fluorescens (Pf) strain IPP202. The results indicated that the recombinant plasmid in IPP202 was very stable after successive diluting culturing and after continuous culturing, There was no significant change in the properties beneficial to plants, such as antifungal activity and plant-colonizing ability as compared with the original strain P303. IPP202 was much more resistant to UV than Bt strain HD73. The control effect in field against cotton boll worm in field was close to that of a locally used Bt-chemical mixture in normal applied concentration. All the data indicated that the engineered Pf strain was a one with prosperous future after further study.

Animals↗

[Effect of gene disruption of aveD on avermectins production in Streptomyces avermitilis].

Recombinant plasmid pCZ2(pKC1139::475 bp aveD) was used for aveD gene disruption in Streptomyces avermitilis 76-9. The plasmid was inserted into the chromosome by homogenous recombination between partial aveD gene in the plasmid and aveD in the chromosome. Disruptants were confirmed by Southern blotting. Shaking flask experiments and HPLC analysis showed that the disruptant produced only four components, which were C5-oxo-avermectin B1a, B1b, B2a, B2b as identified by UV, IR, NMR, and MS. This revealed that both aveD and aveF were not expressed in the disruptant. This is consistent with that aveD and aveF are in a transcription unit. This paper also provided a new genetic method to obtain C5-oxo-avermectin B-producing strain.

Bacterial Proteins↗

[Tissue interaction with bioglass ceramic implanted in the rabbit cornea].

PURPOSE: To evaluate the biocompatibility and 'healing' of Bioglass Ceramic(BGC) in the cornea. METHODS: BGC dicks (8 mm in diameter, 0.5 mm thick, 20-70 microns pore diameter, 37-62% porosity, 7.8 mm radius of curvature) were implanted in 11 New Zealand albino rabbits after a free-hand intralamellar dissection. The eyes were examined by slit-lamp biomicroscope up to seven months postoperatively. The corneas were removed at seven month (one eye at eight month), then were examined by light microscope. RESULTS: Five of 11 dicks of BGC were extruded. All implant of BGC with 51-62% porosity were broken and then extruded. A large part of implants led to markedly edematous with severe degrees of corneal neovascularization within one month postoperatively. The corneal lamella before implants became not clear in all eyes after two months. Lipid deposits occurred in four eyes. It is difficulty to observe the 'healing' process of BGC in the cornea because the BGC is too hard to be cut in spite of being soft by 4% hydrochloric acid for four to ten days before cutting. CONCLUSION: Our findings suggest that BGC with above parameters is not suitable as peripheral keratoprosthetic materials because of its rough, hard, thick and breakable.

Animals↗